Process of preparing glue stocks



Patented Aug. 2, 1932 vireo STATES CHARLES H. CAMPBELL, OF ASPINWALL,PENNSYLVANIA PROCESS OF PREPARING GLUE STOCKS No Drawing.

Glue stock, such as that consisting of hide trimmings, hide fleshings orpieces of chrome tanned hide suitable for the glue making process underthe present practice are subjected to the simmering or boilingoperationwithout previous grinding or other preparation eX- ceptwashing, aciduating and other cleansing processes. g

I have found that by first grinding such stock the extraction of theglue is greatly facilitated and the quality is greatly improved.

This process is the subject inatter of my pending patent applicationsSerial No.

383,164, filed in the United States Patent Gffice August 2, 1929 SerialNo. 425,063, filed January 31, 1930, and Serial No. 486,193, filedOctober 3, 1930. r

The subject matter of this application com- 0 prises a furtherimprovement in the process of grinding the glue stock, and morespecifically it comprises the grinding of the glue stock in the presenceof an abrasive.

Many types of raw glue stock carry high percentages of grease, and evenafter the most careful preparation and washing of the stock this greaseis still present and frequently to such an extent that the mere handlingof the stock will leave a greasy film on the hand. In this condition itis at times diflicult to grind the stock in accordance with theprocessesdescribed in my said patent applications because the grease on thesurface of the stock acts as a lubricant and prevents the mill partsfrom properly biting the stock aand pulling it between the coactingparts. This can be overcome to a degree by exerting a ressure upon thestock during the grinding rocess, but I have discovered that by the useof my present invention better results are obtained.

In my present invention I grind the stock to any size desired by theglue-maker in a suitable grinder or other mill in the presence of asuitable abrasive agent.

I prefer to take the stock after it has been thoroughly washed andtreated and before it is placed in the grinder and sift over the surfaceof the stock a suitable abrasive material, such as a coarse Washed riversand or crushed silica. The abrasive is preferably relativelyApplication filed January 29, 1931. Serial no. 512,220.

sive in accordance with the setting of the mill. For instance, where thesetting is such as to provide a ten thousandths of an inch gap I preferto employ a coarser abrasive than I would employ where the setting isfromthree to fivethousandths of an inch gap.

The abrasive should not be so coarse as to in jur-e the milling surface.

' It. is preferable to accomplish this grinding with abrasive in thepresence of water,

Other abrasives may be used, but

but it is possible that in the case of a stock containing a relativelylarge percentage of moisture the addition of free water may not benecessary.

It is of course necessary to avoid such high speeds of the moving partsof the mill which would tend to cause an emulsification during thegrinding process of the fats liberated. Usually if the speed of themoving parts be kept below two thousand feet per minute there is nodanger of emulsificatio'n.

The employment of the abrasive material enables the grinder parts togrip and pass the material and to size the stock for any subsequent gluemaking operation, including, if desired,.the reduction of the stock to agel.

By" my improvedmethod large tonnages of the most greasy glue stock canbe reduced to the desired size without diliiculty and Without loss ordelay in the grinding operation.

' After the stock has been ground and properly sized the presence of theabrasive in any further grinding or reducing operationis advantageous,as it assists and aids in the cutting of the membranous sacs whichcontain the fatty particles and it also assists in further reducing theparticles of hide fabric. i

The presence of the abrasive in nowise interferes with the subsequentglue-making operation because the abrasive, if it has been properlyWashed and treated before used,

contains no soluble material that will discolor the glue or interferewith any of the subsequent operations.

During the various simmering or boiling 5 operations the abrasive,whether it be sand or any other suitable material, will naturallyseparate itself from the stock and will settle to the bottom of thekettle, when it can be removed by washing or flushing. The last tracesof the abrasive may be easily removed from the glue by filtration. Inthe manufacture of lue the smaller pieces or particles or gel to whichthe stock is reduced the more readily will the glue be cooked out andthe better the quality of the glue, thus enabling the omission of themany successive boilings and treatments which are characteristic of thepresent practice.

Hitherto it has been found impossible to 2 obtain a grinder or millwhich will commercially prepare the stock except at an excessive cost tothe manufacturer. While it has been possible to grind glue stocks in thelaboratory in an experimental way the commercial reduction of the rawstock has always been ditficult and expensive.

What I desire to claim is 1. The process of preparing glue stock whichcomprises adding to the same a granular abrasive material and thensubjecting the stock to disintegration between relatively movablegrinding elements, the relative speed of which elements is such that thefats of the stock are not emulsified.

2. The process of preparing glue stock which comprises adding to thesame in the presence of water a granular abrasive material and thensubjecting the stock to disintegration between relatively movablegrinding elements, the relative speed of which elements is such that thefats of the stock are not emulsified. V

The process of preparing glue stock which consists in adding to the samea granular abrasive material and then subjecting the stocktodisintegration between relatively movable grinding elements to rupturethe membranous sacs by the combined effect of grindin and abrasion, therelative speed of the movable elements being such as to prevent theemulsification of the fats ofthe stock. f Signed at Pittsburgh, Pa, this28 day of January, 1931. V

I CHARLES H. CAMPBELL- 56 a

